A heat treatment method for electron beam physical vapor deposition ceramic microsphere microwave absorbing coating

Abstract

This invention belongs to the technical field of aero-engine coating materials, and relates to a heat treatment method for an electron beam physical vapor deposition ceramic microsphere microwave absorbing coating. After preparing microwave absorbing coatings such as iron and cobalt from ceramic microspheres, heat treatment is necessary to improve the bonding strength between the coating layer and the ceramic microspheres. The method includes the steps of cleaning, dehydration, drying, and high-temperature heat treatment. The high-temperature heat treatment process parameters are selected as follows: the microspheres are placed in a vacuum heat treatment furnace, heated to 1000℃, with a vacuum degree <1×10⁻⁶. ‑2 After holding at 800°C for 4-6 hours, the temperature is cooled to 800°C in the furnace, held for 30 minutes, then cooled to 600°C in the furnace, held for 30 minutes, then cooled to 400°C in the furnace, held for 30 minutes, and finally cooled to room temperature. Once cooled to room temperature, the vacuum chamber is opened, and the electron beam physical vapor deposition ceramic microsphere coating is removed. This high-temperature heat treatment method of the present invention results in a coating with superior adhesion while maintaining the integrity of the microspheres, ultimately improving the material's performance.

Description

Technical Field

[0001] This invention belongs to the technical field of aero-engine coating materials and relates to a heat treatment method for an electron beam physical vapor deposition ceramic microsphere microwave absorbing coating. Background Technology

[0002] Microwave-absorbing coatings generally consist of adhesives, absorbents, and various additives, with the absorbent being the main material and directly determining the coating's microwave absorption performance. According to the principles of microwave absorption, key factors affecting the performance of microwave-absorbing materials include their impedance matching characteristics and attenuation characteristics. Improving electromagnetic wave attenuation requires enhancing the electromagnetic loss characteristics of the absorbing material, while impedance matching necessitates good dielectric matching properties. However, single absorbents suffer from drawbacks such as narrow bandwidth and unstable absorption performance, resulting in microwave-absorbing materials that fall short of expectations. Therefore, research on absorbent surface modification has received widespread attention. Surface modification is a unique method for modifying absorbents, widely used in absorbent surface treatment. It can not only improve the bonding strength of the absorbing material but also reduce its dielectric constant and improve impedance matching, ultimately enhancing its microwave absorption performance. Summary of the Invention

[0003] The purpose of this invention is to provide a heat treatment method for electron beam physical vapor deposition ceramic microsphere absorbing coatings, which addresses the shortcomings of the prior art. The aim is to improve the mechanical properties of the material by causing changes in the crystal structure and microstructure of the ceramic microsphere absorbing coating through vacuum heat treatment.

[0004] To solve this technical problem, the technical solution of the present invention is as follows:

[0005] A heat treatment method for electron beam physical vapor deposition ceramic microsphere microwave absorbing coating is provided, wherein the heat treatment process is as follows:

[0006] Electron beam physical vapor deposition ceramic microsphere microwave absorbing coatings were loaded into a vacuum heat treatment furnace and heated to 1000±100℃ with a vacuum degree <1×10⁻⁶. -2 Pa, after holding at this temperature for 4-6 hours, cool to 800±100℃ in the furnace, hold for 30±5 minutes, cool to 600±100℃ in the furnace, hold for 30±5 minutes, cool to 400±100℃ in the furnace, hold for 30±5 minutes, cool to room temperature in the furnace, and after cooling to room temperature, open the vacuum chamber and remove the electron beam physical vapor deposition ceramic microsphere absorbing coating.

[0007] The coating system is a microwave absorbing coating made of iron, cobalt, nickel, etc.

[0008] The ceramic microspheres have a diameter of 100-200 μm. Ceramic microspheres with this particle size range are easier to coat evenly and are easier to prepare, achieving a good balance between cost and performance.

[0009] The electron beam physical vapor deposition process parameters are: evaporation current 0.8-1.5A, rotation speed 5-10RPM, coating thickness 10-200μm, and ceramic microsphere diameter 100-200μm.

[0010] The method further includes the steps of cleaning and dehydrating the coating prior to heat treatment.

[0011] The cleaning steps are as follows: The iron, cobalt and other microwave absorbing coatings prepared by electron beam physical vapor deposition ceramic microspheres are immersed in 10±5% water-based cleaning agent for 30±5 min, and then the microwave absorbing coatings of electron beam physical vapor deposition ceramic microspheres are immersed in deionized water for 30±5 min.

[0012] Preferably, the water-based cleaning agent is a degreasing agent with a pH of 7±0.5.

[0013] The dehydration and drying steps are as follows: the electron beam physical vapor deposition ceramic microsphere microwave absorbing coating is immersed in an organic solvent for 10±5 min, and then taken out and placed in an oven to dry at 80±10℃ for 15±5 min.

[0014] Preferably, the organic solvent is acetone or ethanol, and its purity is analytical grade.

[0015] The advantages and beneficial effects of this invention are as follows:

[0016] In the heat treatment process of this invention, a multi-stage heat preservation method of 1000-800-600-400℃ is adopted, with a vacuum degree <1×10 -2 Under Pa conditions, by controlling the holding time and temperature at each stage, the transformation from columnar crystals to equiaxed crystals can be achieved, while maintaining the integrity of the microspheres, improving the bonding strength of the coating layer, and ultimately improving the material's performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions implemented in this invention, the accompanying drawings used in the embodiments of this invention will be briefly explained below. Obviously, the drawings described below are merely some embodiments of this invention. Those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0018] Figure 1 The appearance changes of the ceramic microsphere coating before and after heat treatment in Example 1; from Figure 1 As can be seen, after being coated with iron, cobalt, and nickel microwave absorbing coatings, the ceramic microspheres appear black, indicating that the coating is uniform.

[0019] Figure 2 The variation in bonding strength of the ceramic microsphere coatings in Examples 1, 2, 3, and the comparative examples; from Figure 2 As can be seen, the multi-segment insulation method of 1000-800-600-400℃ improves the bonding strength of the coating to over 10MPa. The comparative example changed the maximum insulation parameter compared to other embodiments, thus reducing the bonding strength. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The features of various aspects of the embodiments of the present invention will now be described in detail. In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can also be practiced without these specific details. The technical solutions of the invention will be further described in detail below with reference to embodiments:

[0022] The process conditions for the washing and dehydration drying steps in this embodiment of the invention are the same as those in the comparative example, and the steps are as follows:

[0023] (1) Electron beam physical vapor deposition of ceramic microspheres to prepare microwave absorbing coatings of iron, cobalt, nickel, manganese, etc.: The electron beam physical vapor deposition process parameters are: evaporation current 0.8-1.5A, rotation speed 5-10RPM, coating thickness 10-200μm, and ceramic microsphere diameter 100-200μm.

[0024] (2) Cleaning: After preparing the iron, cobalt, and other microwave absorbing coatings using electron beam physical vapor deposition (EBPV) of ceramic microspheres, immerse them in a 10% water-based cleaning agent for 30 minutes. Then, soak the EBPV-deposited ceramic microsphere microwave absorbing coating in deionized water for 30 minutes. The water-based cleaning agent is a degreasing agent with a pH of 7; specifically, it can be an environmentally friendly water-based cleaning agent, a multi-purpose water-based cleaning agent, or a powerful water-based cleaning agent.

[0025] (3) Dehydration and drying: The electron beam physical vapor deposition ceramic microsphere microwave absorbing coating is immersed in an organic solvent for 10 min, then taken out and placed in an oven to dry at 80℃ for 15 min. The organic solvent is acetone or ethanol with analytical grade.

[0026] Example 1:

[0027] High-temperature heat treatment: The cleaned electron beam physical vapor deposition ceramic microsphere microwave absorbing coating is placed into a vacuum heat treatment furnace and heated to 1100℃ with a vacuum degree <1×10⁻⁶. -2 Pa, after holding at this temperature for 4 hours, cooled to 900℃ in the furnace, held for 30 minutes, cooled to 700℃ in the furnace, held for 30 minutes, cooled to 500℃ in the furnace, held for 30 minutes, and then cooled to room temperature in the furnace. After cooling to room temperature, the vacuum chamber was opened and the electron beam physical vapor deposition ceramic microsphere absorbing coating was removed. The absorbing coating is an Fe coating.

[0028] Example 2:

[0029] High-temperature heat treatment: The cleaned electron beam physical vapor deposition ceramic microsphere microwave absorbing coating is loaded into a vacuum heat treatment furnace and heated to 1000℃ with a vacuum degree <1×10⁻⁶. -2 Pa, after holding at this temperature for 5 hours, cooled to 800℃ in the furnace, held for 30 minutes, cooled to 600℃ in the furnace, held for 30 minutes, cooled to 400℃ in the furnace, held for 30 minutes, and then cooled to room temperature in the furnace. After cooling to room temperature, the vacuum chamber was opened and the electron beam physical vapor deposition ceramic microsphere absorbing coating was removed. The absorbing coating is a Co coating.

[0030] Example 3:

[0031] High-temperature heat treatment: The cleaned electron beam physical vapor deposition ceramic microsphere microwave absorbing coating is loaded into a vacuum heat treatment furnace and heated to 900℃ with a vacuum degree <1×10⁻⁶. -2 Pa, after holding at this temperature for 6 hours, cooled to 700℃ in the furnace, held for 30 minutes, cooled to 500℃ in the furnace, held for 30 minutes, cooled to 300℃ in the furnace, held for 30 minutes, and then cooled to room temperature in the furnace. After cooling to room temperature, the vacuum chamber was opened and the electron beam physical vapor deposition ceramic microsphere absorbing coating was removed. The absorbing coating is a Ni coating.

[0032] Comparative example:

[0033] High-temperature heat treatment: The cleaned electron beam physical vapor deposition ceramic microsphere microwave absorbing coating is placed into a vacuum heat treatment furnace and heated to 800℃ with a vacuum degree <1×10⁻⁶. -2 Pa, after holding at this temperature for 7 hours, cooled to 500℃ in the furnace, held for 30 minutes, cooled to 300℃ in the furnace, held for 30 minutes, cooled to 200℃ in the furnace, held for 30 minutes, and then cooled to room temperature in the furnace. After cooling to room temperature, the vacuum chamber was opened and the electron beam physical vapor deposition ceramic microsphere absorbing coating was removed. The absorbing coating was a Co coating.

[0034] like Figure 2The diagram shows the changes in the bonding strength of the ceramic microsphere coatings in Examples 1, 2, 3, and the comparative example. It can be seen that due to differences in the insulation temperature parameters and the insulation step design parameters, the coating bonding strength in the comparative example is only 6 MPa, while the combination of insulation temperature and insulation step design parameters in Examples 1, 2, and 3 results in coating bonding strengths all above 10 MPa. In the heat treatment process of this invention embodiment, a multi-stage insulation method is adopted: heating to 1000±100℃ in the furnace, holding for 4-6 hours, cooling to 800±100℃ in the furnace, holding for 30-50 minutes, cooling to 600±100℃ in the furnace, holding for 30 minutes, cooling to 400±100℃ in the furnace, holding for 30 minutes, cooling to room temperature in the furnace, under vacuum conditions (vacuum degree <1×10⁻⁶). -2 By controlling the insulation time and temperature at each stage under (Pa) conditions, the bonding strength of the coating layer can be improved. On the other hand, from Figure 2 It can also be seen that, since the maximum insulation parameter was changed in the comparative examples compared to Examples 1, 2, and 3 (the temperature was reduced to 800°C compared to other examples), the bonding strength of the coating was found to be significantly reduced.

[0035] Vacuum degree <1×10 -2 Under Pa conditions, a multi-stage heat preservation method of 1000-800-600-400℃ was adopted. By controlling the heat preservation time and temperature at each stage, the transformation of columnar crystals into equiaxed crystals was achieved, while maintaining the integrity of microspheres and improving the bonding strength of the coating layer to 10MPa, ultimately improving the performance of the material.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A heat treatment method for an electron beam physical vapor deposition ceramic microsphere microwave absorbing coating, characterized in that: The heat treatment process is as follows: Electron beam physical vapor deposition of ceramic microspheres with microwave absorbing coating was loaded into a vacuum heat treatment furnace and heated to 1000°C. 100℃, vacuum degree <1×10 -2 Pa, hold at that temperature for 4-6 hours, then cool with the furnace to 800°C. 100℃, keep warm for 30 minutes After 5 minutes, cool with the furnace to 600°C. 100℃, keep warm for 30 minutes After 5 minutes, the furnace was cooled to 400°C. 100℃, keep warm for 30 minutes After 5 minutes, the furnace was cooled to room temperature. After cooling to room temperature, the vacuum chamber was opened and the electron beam physical vapor deposition ceramic microsphere absorbing coating was removed. The coating system is an iron and cobalt absorbing coating.

2. The heat treatment method according to claim 1, characterized in that: The diameter of the ceramic microspheres is 100-200 μm.

3. The heat treatment method according to claim 1, characterized in that: The electron beam physical vapor deposition process parameters are: evaporation current 0.8-1.5A, rotation speed 5-10RPM, coating thickness 10-200μm, and ceramic microsphere diameter 100-200μm.

4. The heat treatment method according to claim 1, characterized in that: The heat treatment method further includes the steps of cleaning and dehydrating the coating prior to heat treatment.

5. The heat treatment method according to claim 4, characterized in that: The cleaning steps are as follows: The iron and cobalt microwave absorbing coating prepared by electron beam physical vapor deposition of ceramic microspheres is immersed in 10... Clean 30 minutes in 5% water-based cleaning agent After 5 minutes, the electron beam physical vapor deposition ceramic microsphere microwave absorbing coating was immersed in deionized water for 30 minutes. 5 minutes.

6. The heat treatment method according to claim 5, characterized in that: Water-based cleaning agents have a pH of 7. 0.5% degreasing agent.

7. The heat treatment method according to claim 4, characterized in that: The dehydration and drying steps are as follows: The electron beam physical vapor deposition ceramic microsphere microwave absorbing coating is immersed in an organic solvent for 10 minutes. 5 minutes, then remove and place in an oven at 80°C. Dry at 10℃ for 15 minutes 5 minutes.

8. The heat treatment method according to claim 7, characterized in that: The organic solvent is acetone or ethanol, and its purity is analytical grade.

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